There is no boolean type in Cairo but you can return a `felt` with value 1. For example:


`func test() -> (success: felt):`


 `return (1)`


`end`


ㅤ
_This answer was originally posted on [Triality](https://triality.org/question/686)_

Just to add to the existing valid answer:


StarkWare also provides a library for this: `starkware.cairo.common.bool` . You can import it with `from starkware.cairo.common.bool import TRUE, FALSE` and then use `TRUE` and `FALSE`in your code. In reality, the library simple maps true to 1 and false to 0 (<https://github.com/starkware-libs/cairo-lang/blob/master/src/starkware/cairo/common/bool.cairo>)


ㅤ
_This answer was originally posted on [Triality](https://triality.org/question/686)_

Is there an equivalent of return (true) in cairo on Starknet?


ㅤ
_This question was originally posted on [Triality](https://triality.org/question/686)_

Cairo: How to return true from a function?

is there an example of migration scripts somewhere ?

_This question was originally posted on [StarkNet Discord](https://www.newton.so/view?tags=discord)_

Is there an example of migration scripts somewhere [Cairo/StarkNet]?

How do I connect my DAPP to Starknet testnet using starknetjs?

Does anyone know how I can create an array and populate it in the python hint?
Basically something like


```cairo
let (my_array: felt*) = alloc()
%{
  ids.my_array = [1, 2, 3]
%}
```


How can I create an array and populate it in the hint Cairo lang/Protostar?

Why am I getting the error message `“ArgumentsLengthError: The number of the given arguments (0) do not match what is defined in the ABI (1)”`


ApeWorX: Why am I getting the error message "ArgumentsLengthError"?

This isn't a starknet question, but raw cairo. is it possible to use a pointer reference like let, and set it to a pointer with a hint, without doing a memory allocation?

looks like the answer is yes, but you do need to assign a reference when you declare a pointer reference with let, but that doesn't alter the memory

e.g.

```python
let s : felt* = cast(ap, felt*)
{
	ids.s = some_other_reference
}
```

the `cast(ap, felt*)` does nothing, just satisfies the compiler by having something on the rhs of a let

a pointer with a hint, without doing a memory allocation

I have a question about creating elements via a function vs doing them directly. Here's a small gist: [https://gist.github.com/rlkelly/6cc8f4cce06762c3153fc7e3acaf9429](https://gist.github.com/rlkelly/6cc8f4cce06762c3153fc7e3acaf9429)

```
%lang starknet

from starkware.cairo.common.alloc import alloc

struct Foo:
    member val: felt
end

func make_foo(value: felt) -> (foo: Foo):
    let foo = Foo(
        val=value,
    )
    return (foo)
end

func make_foo_array() -> (entry: Foo*):
    let (struct_array : Foo*) = alloc()

    let foo0 = make_foo(0)
    assert struct_array[0] = foo0
    return (struct_array)
end

@external
func test_make_foo{syscall_ptr : felt*, range_check_ptr}():
    let (foo_array) = make_foo_array()
    return ()
end

#   File "starkware/cairo/lang/compiler/preprocessor/preprocessor.py", line 1223, in visit_CodeElementCompoundAssertEq
#  starkware.cairo.lang.compiler.preprocessor.preprocessor_error.PreprocessorError: contracts/tests/test_foo.cairo:22:5: Cannot compare '__main__.Foo' and '(foo : __main__.Foo)'.
```

i'm curious why `__main__.Foo` and `(foo : __main__.Foo)` are typed differently

it appears like `let foo =` and `let (foo) =`  allocate memory differently

Creating Elements via a function

Hello! This is day 11 of the 17 days of the Cairo Challenge. And I have no idea how to solve the [playground](https://www.cairo-lang.org/playground/) exercise “Address of locals”.  Perhaps you can help me?

```
// When Cairo needs to retrieve the *address* of a local variable,
// it needs to be told the value of the frame pointer register, fp
// (see [here](https://cairo-lang.org/docs/how_cairo_works/functions.html#fp-register)).
//
// This can be done by setting a reference named __fp__ to the value, which
// can be obtained using the library function get_fp_and_pc().
//
// 1. Try to run the code as-is, and make sure you understand the error.
// 2. Uncomment the line setting __fp__, and run again.
//    The code should now work and you should be able to see that `x` was set
//    to 1000.
// 3. Uncomment the line calling foo() and try to run the code.
//    Fix the code by adding exactly one word to it.
//    Hint: Revisit the "Revoked references" challenge.

from starkware.cairo.common.registers import get_fp_and_pc

// Returns a^3 for a != 0 and 1 otherwise.
func foo(a) -> (res: felt) {
    if (a == 0) {
        return (res=1);
    } else {
        return (res=a * a * a);
    }
}

func main() -> () {
    alloc_locals;

    // let (__fp__, _) = get_fp_and_pc();
    local x: felt;
    // let (x) = foo(a=10);
    local y: felt* = &x;
    assert [y] = 1000;
    return ();
}
```

---

> Answers to this question are a part of the ✨ 17 days of Cairo Lang with Playground & Newton. ✨
> 

*Vote for your favorite answer - the best answer will win a $10 award. A new day – a new reward! During the next 17 days, our goal is to attract more developers to the Cairo language and to systematize the knowledge of Cairo lang. [Read rules](https://www.notion.so/17-days-of-Cairo-Lang-with-Newton-550dfcda6a2d449ca468be293c776578)*

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Cairo: How to return true from a function?

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